This picture of a glowing cat has not been altered in any way. The cat, on the other hand, has been altered quite a bit. A team of researchers has genetically engineered it to express green fluorescent protein (aka "GFP," originally found in jellyfish), which makes the cat glow green under ultraviolet light.

But GFP isn't the only extra-species gene this cat is carrying — it's also packing a gene called TRIMCyp, originally found in monkeys. By giving the gene to the cats, the researchers hope to shed light on how they might combat diseases like HIV/AIDS — not just in felines, but in humans, too.

Cats, like humans, can develop AIDS. In cats, AIDS is preceded by feline immunodeficiency virus (FIV), while in humans it's preceded by human immunodeficiency virus (HIV).

Like HIV, FIV leads to AIDS by sapping the body's ability to combat infection; in both humans and cats, a special class of proteins known as "restriction factors" (which are usually very effective in defending against viruses) are effectively useless when pitted against HIV and FIV, respectively. But what if one species' restriction factors could be used to defend against another species' immunodeficiency virus?

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Well guess what — they can. It turns out that one of the rhesus macaque's restriction factors, TRIMCyp, can actually block cell infection by FIV.

Now, a team of researchers led by Eric Poeschla of the Mayo Clinic College of Medicine has genetically engineered a littler of cats that were born carrying the TRIMCyp gene.

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How do they know the cats are carrying the monkey's gene? They labeled it with GFP — hence the glow. (This picture shows the genetically modified cat featured up top alongside a non-genetically modified cat at five months of age.)

The team genetically modified the cats by inserting the genes into an adult, female cat's donor eggs before they were even fertilized. The eggs were then placed into the womb of a foster mother where they developed into transgenic cats like the one pictured above. The technique is known as "gamete-targeted lentiviral transmission," and — until now — had never been successfully performed on a carnivore.

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As their corporeal glow indicates, the cats are clearly expressing the GFP-labeled TRIMCyp gene; according to the researchers, transgene expression has been observed in all of the cat organs they've tested (16 in total), including in the main lymphoid organs (comprising the lymph node, thymus, and spleen), where HIV tends to target infection-fighting T-Cells in humans.

Poeschla's team has already demonstrated that white blood cells taken from the transgenic cats are protected from FIV; the next step is to give the virus to the cats themselves, to confirm that they are, in fact, immune to it. Their findings could help them and other researchers develop and test similar approaches to protecting humans from infection with HIV.

"One of the best things about this biomedical research is that it is aimed at benefiting both human and feline health," said Poeschla. "It can help cats as much as people."

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The research team's results are published in the latest issue of Nature MethodsImages via Nature Methods